Deshpande, A. S., Shchukin, D. G., Ustinovich, E., Antonietti, M., & Caruso, R. A. (2005). Titania and mixed titania/aluminum, gallium, or indium oxide spheres: sol-gel/template synthesis and photocatalytic properties. Advanced Functional Materials, 15(2), 239-245. doi:10.1002/adfm.200400220.